To reduce air pollution, engine exhaust emissions standards have become increasingly more stringent. Aftertreatment devices have been developed to satisfy these increasingly stringent standards. For example, catalytic converters have been used to reduce the concentration of pollutant gases (e.g., hydrocarbons, carbon monoxide, nitric oxide, etc.) exhausted by engines. U.S. Pat. No. 5,355,973, which is hereby incorporated by reference, discloses an example catalytic converter. With respect to diesel engines, diesel particulate filters (DPF's) have been used to reduce the concentration of particulate matter (e.g., soot) in the exhaust stream. U.S. Pat. No. 4,851,015, which is hereby incorporated by reference, discloses an example diesel particulate filter. Other example types of aftertreatment devices include lean NOx catalyst devices, selective catalytic reduction (SCR) catalyst devices, lean NOx traps, or other device for removing for removing pollutants from engine exhaust streams.
Aftertreatment devices can be mounted within engine exhaust system components. To allow aftertreatment devices within exhaust system components to be serviced or replaced, the exhaust system components are often provided with access joints. A typical access joint is defined between two sections of an exhaust system component. The sections have flanged ends that are clamped together (e.g., by a v-band clamp) to form the access joint. By removing the clamp, the two sections can be disconnected to open the joint and provide access to an aftertreatment device within the engine exhaust component. It is desirable for access joints to be relatively leak-free.